Meniscal lesions are frequent during sport practice. Although the lateral meniscus is affected in only 25% of all meniscal lesions, lateral lesions are usually known to have poor clinical outcome. Our monocentric study consisted in the systematic evaluation of all patients treated in our unit for a unique lesion of the lateral meniscus in an otherwise normal knee. Follow-up was of at least ten years. Functional results were rated with four grades currently used in traumatology practice. Statistical analysis was conducted to identify predictive factors of poor outcome. Thirty-nine patients were included. Functional assessment showed 12% of excellent, 41% of good, 35% of mediocre and 12% of poor results on Arpege's score; 65% of good and excellent and 35% of mediocre results on Lysholm's score. The average subjective IKDC score 58±15, the objective score showed 0% of A, 88% of B and 12% of C. The average Koos score was 83.7±17. Better outcome was noted in patients with horizontal injuries (P=0.04) or in patients with central segment injury (P=0.05). Similar data concerning the poor functional outcome of lateral meniscus tears have been published. Only two thirds of patients claim good or excellent results after 10 years.